WASHINGTON (CNN) -- Federal law enforcement has given the "all clear" at the Washington Navy Yard on Thursday morning, after a lockdown forced workers to hold-in-place and filled the Southeast D.C. neighborhood with police and ambulance vehicles.
The U.S. Navy tweeted that the facility was under lockdown around 8 a.m. EDT. The complex is the site of a 2013 shooting where 12 people were killed.
#BREAKING: @NavalDistWashington Navy Yard on lockdown/shelter in place. No incident can be confirmed as of yet. More to follow.
— U.S. Navy (@USNavy) July 2, 2015
DC Police said in a statement around 10:15 a.m. that the search of the Navy Yard has been completed, and that no evidence of shooting or injured personnel have been found.
Police said a call was placed from inside a Navy Yard building reporting possible gun shot sounds, which is what prompted the lockdown and investigation.
DC Mayor Muriel Bowser, DCPD Police Chief Kathy Lanier and Vice Admiral Dixon Smith, commander of naval installations, briefed reporters around 11 a.m., roughly an hour after the all clear came out and a search of Navy Yard's facilities had been completed.
"At this time there is no evidence of gun shots, there is no evidence of a shooter and there is no evidence of any victims today," Bowser said.
The officials praised response time of emergency officials as well as Navy Yard workers, who have seen protocol change since the 2013 shooting.
"It appears that all the things we tried to correct and make better from the last incident went well," Lanier said.
Police searched building 197 on Thursday morning, the same building where the 2013 Navy Yard shooting took place, a source with DC's Metropolitan Police Department tells CNN.
The law enforcement source said the original 911 call reported a shooting on the second floor.
Navy Commander Scott Williams, who was at the Navy Yard on Thursday morning and during the attack two years ago, told CNN's "New Day" that the scene unfolding around the complex was "pretty much a mirror image of 2013".
Naval Architect Jordan Rongers told CNN that the response and evacuation "pretty much the same thing as happened three years ago, but I think the response has been much better," citing better protocols and security.
In a preventative measure, officials closed Pennsylvania Avenue in front of the White House. A law enforcement official says the move is a standard security precaution in light of potential navy yard incident under investigation.
A defense official says the Pentagon has not raised its security posture here on the Pentagon complex in reaction to the situation at Navy Yard, but they are keeping a close eye on what is going on.
Dozens of police and ambulance vehicles surrounded the Washington Navy Yard on Thursday morning. Bystanders tweeted photos of the scene, though official details on the incident we're scarce as of Thursday morning.